Gastric motility Flashcards Preview

Physiology > Gastric motility > Flashcards

Flashcards in Gastric motility Deck (53):
1

What is gastroparesis?

Decreased gastric motility (NOT a total shut down)

2

What is the migrating motor complex?

GI motor activity that starts in the stomach, and sweeps over the upper GI tract about every 90 minutes

3

What happens to the migrating motor complex during the fed state?

No longer migrating--constant motor activity

4

What are the three general types of GI motor activity?

Storing
Churning
Emptying

5

What causes the storing effect of the GI tract?

Tonic contractions

6

What are the two steps of gastric storing/filling?

Receptor relaxation
Gastric accommodation

7

What happens during the receptive relaxation phase of gastric storing? (2)

Relaxation of LES and stomach in anticipated by food

Rise in gastric volume, without change in pressure

8

What is the innervation of receptive relaxation reflex of the stomach?

Vagus

9

What initiates the receptive relaxation of the stomach?

Swallowing

10

What is the signalling used in receptive relaxation to relax the LES?

Non Cholinergic and nonadrenergic (NO mediated)

11

What happens in gastric accommodation?

Stomach relaxation in response to gastric filling

Dilation of fundus

12

What primarily regulates gastric accommodation? What modulates it?

ENS

Vagus

13

What happens to volume/pressure in gastric accommodation?

Increase in volume without increase in pressure (just like the bladder)

14

What are the three parts of gastric churning?

Propulsion
Retropulsion
Grinding

15

What is propulsion part of gastric churning?

Movement of stomach contents against the pyloric region

16

What happens to the pyloric sphincter during gastric churning?

Shuts down

17

What initiates the propulsion part of gastric churning?

Pacemaker cells near the greater curvature of the stomach

18

What is retropulsion part of gastric churning?

Pulverization and shearing of food particles by contractions

19

What is the overall goal of gastric churning?

Increased surface area of food

20

What happens in the grinding phase of gastric churning?

Food is trapped in the antrum

21

When do particles larger than 2 mm pass into the duodenum?

Interdigestive period (2 hours later)

22

The rate of gastric emptying is dependent on what?

The content of ingested material

23

What happens to rate of gastric emptying with increasing protein and fat?

Lowers rate of emptying

24

What controls the rate of gastric emptying?

Neuronal and hormonal control

25

What three hormones play a role in gastric emptying?

1. Secretin
2. CCK
3. Gastrin

26

What are the four NTs utilized in gastric emptying?

Ach
NO
5HT
VIP

27

HCl in the duodenum stimulates what hormone to be secreted? Result?

Secretin = impaired gastric emptying, increase HCO3 production from the pancreas

28

Fat in the duodenum primarily stimulates what hormone to be secreted? Result?

CCK --impaired gastric empyting

29

Protein in the stomach stimulates what hormone to be secreted? Result?

Gastrin-- impaired gastric emptying

30

Duodenal distension in the duodenum stimulates what? Result?

ENS--impaired gastric emptying

31

Vagal stimulation in the duodenum stimulates which three neurotransmitters that impair gastric emptying?

Ach, opioid, 5HT = impaired gastric emptying

32

What are the four targets of CCK?

Gallbladder
Pancreas
Stomach
Sphincter of Oddi

33

What is the effect of CCK on the gallbladder?

Contraction

34

What is the effect of CCK on the pancreas?

Acinar secretion

35

What is the effect of CCK on the the stomach?

Reduced emptying

36

What is the effect of CCK on the sphincter of Oddi??

Relaxation

37

Gastroparesis is frequently associated with what?

Impairments of the pyloric region or pyloric sphincter itself (DM neuropathy/ infantile pyloric stenosis)

38

What are the events involved in emesis?

Afferent fibers activated, which trigger the vomiting center, causing a reverse wave of peristalsis

39

What is the stimulus for an emetic response?

Irritation of the GI mucosa

40

What are the nerve fibers activated in emesis?

Afferent fibers

41

What is the purpose of increased saliva prior to emesis?

Lubricates
Increases pH
Mucin protection

42

The emetic response is coordinated by what nerve?

Vagal afferents and emetic center of the brain

43

What is the purpose of secondary peristalsis in emesis?

Returns esophageal material back to the stomach

44

What are the two stimuli for secondary peristalsis?

Stretch and lower pH

45

What are the four key neurotransmitters for sensory information from the gut to be relayed back to the CNS?

5-HT, Ach, histamine, and D2

46

What muscarinic receptors are located in the chemoreceptive trigger zone?

M1

47

Motion sickness is mediated through what two receptors on the cerebellum?

Histamine and Ach

48

Why can uncontrolled DM lead to gastroparesis?

Neuropathy

49

What is the key neurotransmitter in the intestines?

5HT

50

What happens in retching?

occurs when the upper esophageal sphincter does not relax and the contents of the stomach are not expelled

51

What are the three receptors in the chemoreceptor trigger zone (which stimulates the emetic center of the brain)?

5HT, D2, M1

52

What are the neurotransmitter receptors on the NTS (which stimulates the emetic center of the brain)?

5HT
D2
M1
H1

53

Vagal stimulation in the duodenum stimulates which two hormones that promote gastric emptying

NO, VIP = promotes gastric emptying